Cluster bombs are part of a category of munitions designed to be «sprayed» over a wide perimeter. The principle is simple: a large container (bomb, shell, missile or rocket) is filled with small bomblets (submunitions). The container opens and the submunitions are scattered over a broad area creating a blanket of explosions which can cover several hectares. Between 5 and 30% (sometimes up to 40%) do not explode on impact.